Search found 1746 matches

by dyarker
Sun Dec 03, 2023 1:45 pm
Forum: General Discussion
Topic: Simple power supply, modular design
Replies: 9
Views: 88420

Re: Simple power supply, modular design

Like I said, the transformer alone blows the fuse sometimes.
Yeap, you said that.

:? :?
by dyarker
Thu Nov 30, 2023 10:07 pm
Forum: General Discussion
Topic: Simple power supply, modular design
Replies: 9
Views: 88420

Re: Simple power supply, modular design

[caps 20 mili F, that's 10k microF + 10 microF, common black can Did skip "k" on second 10 by accident? I'm surprised you don't blow the 3A (or 4A) fuse every time it is turned on. (unless you're not waiting for caps to bleed off sometimes) With caps that large the in-rush of current is H...
by dyarker
Tue Nov 28, 2023 2:14 pm
Forum: General Discussion
Topic: Crypto Mining
Replies: 8
Views: 41196

Re: Crypto Mining

The money is in selling hotspot hardware to stupid people.
by dyarker
Thu Nov 09, 2023 1:37 am
Forum: General Discussion
Topic: Assistance required for circuit design
Replies: 11
Views: 20225

Re: Assistance required for circuit design

1. DC electronics is basically simple algebra and knowing when to use which formula. 2. Semiconductors add some more rules, but still not too hard for ON/OFF. 3. DC with capacitors and inductors brings in curves, but still algebra. 4. Next step would be linear/analog AC like audio amplifiers. 5. AC ...
by dyarker
Thu Nov 09, 2023 1:03 am
Forum: General Discussion
Topic: Assistance required for circuit design
Replies: 11
Views: 20225

Re: Assistance required for circuit design

Q2 and Q3 are 2N2222A. In TO-18 package. They are 600 mA maximum current and 1.8 W maximum heat disipation at 25°C. At 417 mA, V SAT is 1V = 0.417W. Assuming the circuit will be in an enclosure, and you'll ride on warm days the transistor temperature will be higher; the maximum dissipation must be d...
by dyarker
Wed Nov 08, 2023 7:08 pm
Forum: General Discussion
Topic: Assistance required for circuit design
Replies: 11
Views: 20225

Re: Assistance required for circuit design

5W / 12V = 0.416A (seemed like a lot of current for LEDs till I looked at the ad for the light you're using) Instead of one high power transistor for Q2, I'll 2 smaller ones. One for bike and one for trailer. (It will okay if trailer is not plugged in.) I will redo the schematic, do the calculations...
by dyarker
Sun Nov 05, 2023 12:51 am
Forum: General Discussion
Topic: Assistance required for circuit design
Replies: 11
Views: 20225

Re: Assistance required for circuit design

How it works: Q1 is PNP, it is on when base is more negative than emitter. Q2 is NPN, it is on when base is more positive than emitter. On is collector/emitter current caused by a smaller base current when base/emitter is forward biased (as in first two sentences). Q2 switches the LED current. To ke...
by dyarker
Sat Nov 04, 2023 9:52 pm
Forum: General Discussion
Topic: Assistance required for circuit design
Replies: 11
Views: 20225

Re: Assistance required for circuit design

I take it you want brake light from lo brake? NV_LED.png If you have individual LEDs I need more info to calculate R-Limit. If the brake light is an assembly rated 12V then R-Limit is built in, we don't need a separate R-Limit. Still need the current rating of the brake light to calculate RQ. Cheers,
by dyarker
Sat Nov 04, 2023 1:46 am
Forum: General Discussion
Topic: Assistance required for circuit design
Replies: 11
Views: 20225

Re: Assistance required for circuit design

Bike frame is common for both though?

Easier if bulb socket is not connected to frame.
by dyarker
Fri Nov 03, 2023 3:39 pm
Forum: General Discussion
Topic: Assistance required for circuit design
Replies: 11
Views: 20225

Re: Assistance required for circuit design

5V and 12V are voltages. Current is measured in Amperes (A) or milliAmperes (mA) How much current does the 12V load need? How much current can brake spare for the control circuit? It could be two transistors and two resistors. Or, a relay with 5V coil and use the NC (normally closed) contacts for th...
by dyarker
Tue Oct 03, 2023 8:22 pm
Forum: Job Board
Topic: Freelance circuit designer needed
Replies: 5
Views: 51906

Re: Freelance circuit designer needed

OP never came back since 2014, unlikely job is still available or even OP seeing the question.

Cheers,
by dyarker
Thu Sep 21, 2023 2:31 am
Forum: General Discussion
Topic: Looking for a new gadget....maybe new idea ?
Replies: 11
Views: 44735

Re: Looking for a new gadget....maybe new idea ?

I guess a cell phone interface is possible...
No, no PTT.
For testing wire pairs I always used a tone generator and inductive pickup.

Cheers,
by dyarker
Thu Sep 21, 2023 2:23 am
Forum: General Discussion
Topic: Stepper Driver
Replies: 1
Views: 18241

Re: Stepper Driver

I would think DIR would stay the same or just (like its rise/fall time be completed) before current is switched to next or previous pole of motor.

Cheers,
by dyarker
Thu Jul 20, 2023 6:36 pm
Forum: Nuts & Volts Magazine Discussions
Topic: Western Electric Vacuum Tubes
Replies: 32
Views: 337175

Re: Western Electric Vacuum Tubes

oooooh ... so far back..
suppressor grid keeps electrons from bouncing off the plate
of course those that strike the suppressor don't get to the plate at all
(like I said memory is very old on this. never heard it called outer anode though. good thing this thread is just for curiosity)